1. Field of the Invention
The present invention relates generally to vehicle lamps mounted in vehicles such as automobiles. More particularly, the invention relates to a vehicle lamp fitted with a reflector which is formed separately from a lamp body and tilted by an aiming mechanism.
2. Description of the Related Art
Vehicle lamps of the sort required to regulate light distribution characteristics of the light emitted from light sources as in the case of automobile headlamps are provided with an aiming mechanism for adjusting an optical axis of emission light. Conventionally, a reflector for supporting an electric bulb as a light source is installed in a lamp body separately from the lamp body and the aiming mechanism is employed for tilting the reflector horizontally and vertically with respect to the lamp body. Consequently, such an aiming mechanism is fitted with a fulcrum portion for tiltably supporting the reflector, a horizontal and a vertical aiming portion for respectively tilting the reflector horizontally and vertically. In particular, a pivot structure as a universal joint structure using a spherical pivot and a ball seat is employed in the fulcrum portion for making the reflector tiltable in the horizontal and vertical directions which are perpendicular to each other.
Heretofore, a pivot structure of the kind mentioned above, has been formed with a spherical pivot provided on the lamp body and reflector, and the ball seat provided on the other, so that the spherical pivot is received by the ball seat. In order to accomplish this construction, the spherical pivot and the ball seat have been formed separately from the lamp body and the reflector and then secured to the lamp body and the reflector, respectively. As shown in FIG. 8, for example, a spherical pivot 110 is secured to the inner surface of a lamp body 101, whereas a ball seat 120 is secured to a reflector 103. In this example, a strut portion 113 is formed integrally with a spherical portion 112, and a screw portion 114 coupled to the end portion of the strut portion 113 is screwed into a screw hole 115 bored in the inner surface of the lamp body 101 so as to secure the spherical pivot 110 to the lamp body 101. Further, a ball seat 120 is formed with a cylindrical portion 121 with one end portion formed like a circular mortar, and a fitting portion 122 with the other portion having a lance 123 smaller in diameter than the cylindrical portion, the other end portion being securely fitted into the hole 126 of a stem 125 projecting in the back of the reflector 103. When the spherical portion 112 of the spherical pivot 110 is forced into the cylindrical portion 121 of the ball seat 120 from the leading end portion of the cylindrical portion 121, the spherical pivot 110 is received by the ball seat 120, which causes the reflector 103 to be tiltably supported by the lamp body 110.
As the conventional fulcrum portion has been arranged so that the spherical pivot and the ball seat formed separately from the lamp body and the reflector are respectively secured to the lamp body and the reflector, not only the number of parts but also the number of assembling steps tends to increase, which results in the problem of increasing cost in the vehicle lamp. Therefore, it has been taken into consideration to form the spherical pivot and the ball seat integrally with the lamp body and the reflector, respectively. However, since the pivot is spherical or substantially spherical, undercutting easily develops in the mold when an attempt is made to resin-mold the spherical pivot integrally with the lamp body or the reflector, causing difficulties in the resin-molding process. In particular, when the spherical pivot 110 is formed so as to project in the direction of parting molds for resin-molding the lamp body 101 and the reflector 103, that is, when it is normally formed so as to project along the longitudinal direction of the lamp, the undercutting cannot be dealt with unless a slider is used for the mold. In other words, any attempt to force these resin-molding component parts to be drawn out without using any slider would result in difficulty in molding a spherical pivot having the required quality. For this reason, the mold structure has heretofore become complicated and failed to facilitate the molding operation. On the other hand, molding the ball seat 120 using the sliders still remains difficult because the cylindrical portion 121 is formed like a circular mortar, making it necessary to force the component parts to be drawn out. Moreover, errors develop in the shape and dimensions of the molded ball seat. Further, accurate aiming becomes hardly attainable because backlash and deviation are produced when the aiming mechanism is installed.